Beacon Lesson Plan Library

More Bait for Your Buck!

Denise West


This activity, intended for use with a science lesson using invertebrates, poses the problem of where to buy earthworms. Students estimate and weigh worms to determine where they can purchase the heaviest ones. Compile results in a double bar graph.


The student knows measurement concepts and can use oral and written language to communicate them.

The student solves real-world problems involving measurement of the following:length (for example, eighth-inch, kilometer, mile); weight or mass (for example, milligram, ton); temperature (comparing temperature changes within the same scale using either a Fahrenheit or Celcius thermometer); and angles (acute, obtuse, straight).

The student solves real-world problems involving estimated measurements, including the following: length to nearest quarter-inch, centimeter; weight to nearest ounce, gram; time to nearest one-minute interval; temperature to nearest five-degree interval; and money to nearest $1.00.

The student chooses reasonable titles, labels, scales and intervals for organizing data on graphs.

The student generates questions, collects responses, and displays data on a graph.

The student analyzes and explains orally or in writing the implications of graphed data.


-Primary balances
-Gram stackers
-Earthworms (segmented worms) from two different stores
-Notebook paper
-Crayons or markers
-Chart paper/butcher paper
-Graph paper
-Two different colors of sticky notes (photocopies of earthworms may be used)
-Copy of More Bait for Your Buck! form for each student


1. Gather materials for activity.
2. Make copies of worksheet for students to record estimates and actual weights of earthworms.
3. Prepare a bulletin board for use as a double bar graph.


1. Tell students, “I am going fishing, and I want to use fat, juicy earthworms for bait in order to catch the biggest fish.”

2. Ask students if they have ever been fishing. Discuss whether it would be better to use skinny earthworms or fat, juicy ones for bait.

3. Ask students how much they think an earthworm weighs.

4. Explain to students that you have purchased earthworms from two different stores (referred to as Store A and Store B) and would like for the students to help determine which store sold the heaviest earthworms.

5. Open a container of live earthworms from each store, and hold an earthworm from each in your hand for the students to see.

6. Ask students to share their experiences weighing objects, and explain that they will find the mass of live earthworms using balance scales and gram stackers.

7. Discuss mass in grams, comparing it to kilograms, milligrams, and customary units of weight (ounce, pound, and ton). Write the word grams and the abbreviation (g) on the chalkboard / dry erase board or chart paper.

8. Divide students into pairs or small groups.

9. Distribute activity materials, and make sure that each student has two earthworms (one from each store).

10. Review the way a balance scale works. Model weighing several small objects. Also select several students to model weighing objects.

11. Ask students if they think all earthworms weigh the same. Students should estimate the mass in grams of their earthworms and record the estimation of each on the form provided.

12. Students cooperatively weigh and record their earthworms’ actual mass.

13. Review the procedure for making a double bar graph. Choose reasonable titles, labels, scales and intervals for organizing data.

14. Graph class data. Students will create a bulletin board double bar graph using two different colors of sticky notes, or photocopies of earthworms. Make sure their names are on them.

15. Individually, students will transfer the data to graph paper.

16. Compare the data on the graph to detect any similarities or differences. Discuss whose earthworm weighed the most, the least, the same, how many weighed more or less than yours, and which weighed more--the earthworm from Store A or Store B. Allow ample time for discussion and feedback.

17. Retrace the steps taken while doing this activity. Review signal words to show time order (first, next, then, last, etc.). Encourage students to discuss what they liked best about the lesson, what they liked least, and what they learned.

18. Students write a summary of the activity drawing conclusions on where to buy the heaviest earthworms and then illustrate it on a sheet of paper.

19. Students share with the class.


Watch to see if students use the balance correctly. Ask how they knew their earthworms did weigh X amount of grams. Listen to their answers regarding graphed data. Discuss students' estimates, and decide if they are reasonable. The students completed worksheets will be checked by the teacher for reasonable weights (estimates and actual). Acceptable individual graphs must include reasonable titles, labels, scales and intervals for organizing data, and summaries must include a conclusion of where to buy the heaviest earthworms.


1. Estimate the number of segments each earthworm has.
2. Use a magnifying glass to verify the estimation by counting.
3. Graph the information.
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